Wiki’s definition of astrophysics is comprehensive. Contemporary astrophysics often is associated with Big Science programs involving both observational and theoretical work by large, interdisciplinary teams.
Astrophysics is the branch of astronomy that employs the principles of physics and chemistry “to ascertain the nature of the heavenly bodies, rather than their positions or motions in space.” … Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.
Yesterday, Space.com posted a take on the subject as well: “What is Astrophysics?”
Astrophysics is a branch of space science that applies the laws of physics and chemistry to explain the birth, life and death of stars, planets, galaxies, nebulae and other objects in the universe. It has two sibling sciences, astronomy and cosmology, and the lines between them blur.
In the most rigid sense:
- Astronomy measures positions, luminosities, motions and other characteristics.
- Astrophysics creates physical theories of small to medium-size structures in the universe.
- Cosmology does this for the largest structures, and the universe as a whole.
The goals of astrophysics make the news all the time because they address timeless Big Questions.
Astrophysicists seek to understand the universe and our place in it. At NASA, the goals of astrophysics are “to discover how the universe works, explore how it began and evolved, and search for life on planets around other stars,” according NASA’s website.
NASA states that those goals produce three broad questions:
- How does the universe work?
- How did we get here?
- Are we alone?
The Space.com article also provides some history of the subject and the career path.
The increasing use of visualization really makes space science fascinating!
Update [1-12-2018] Paul Sutter1 posted an article at Space.com on this topic: “What Does It Take to Be an Astrophysicist?” His article includes two YouTube videos. Excellent commentary on the journey of becoming a scientist — process, perspective, perseverance.
 Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI science center. Sutter is also host of Ask a Spaceman and Space Radio, and leads AstroTours around the world. Sutter contributed this article to Space.com’s Expert Voices: Op-Ed & Insights.